A support for a telephone handset in which a handset rests on a pin that terminates in a plate is described in European Patent No. EP 0 526 715. The plate and the pin can be made of a transparent or translucent plastic. The use of a translucent or transparent material makes it possible to illuminate the plate and possibly also the pin by a light source appropriately disposed inside the telecommunications terminal. This can be used, for example, for the visual signaling of a call.
In contrast, the telecommunications terminal according to the present invention has the advantage that at least one key made of transparent material is provided, and that the light source illuminates the key as a function of the operating state of the telecommunications terminal if actuating the key will trigger a function assigned to this operating state. In this way, individual keys can separately signal different states of the telecommunications terminal. As only those keys are illuminated that trigger a function assigned to the operating state concerned, this makes it easier for the user to select the control functions that are possible in this operating state by actuating the appropriate keys, and thus increases functional clarity.
It is especially advantageous that the light source visually signals an incoming call, that the light source illuminates the key when there is an incoming call, and that the incoming call is answered by actuating the key. In this way, the user knows immediately which key is to be actuated for an incoming call, since only this key is illuminated. Thus the user does not first have to search for the required key, with the result that functional clarity for the user is increased and the time needed to answer the call is reduced.
A further advantage is that the key rests on a switching mat that is transparent at least in the region of the key, and that the key encompasses a transparent thrust pad that serves to establish contact when the key is actuated. In this way, no additional light-conducting bodies are needed for the key to be illuminated by the light source, since the switching mat and the thrust pad also function as light guides. This eliminates the material and production cost and the space consumption associated with an additional light guide. The smaller space requirement is particularly advantageous for telecommunications terminals designed as mobile telephones, where it is especially important to keep size to a minimum.
Another advantage is that the printed circuit board has a bore in the region of the key, and that the light source is so arranged on the opposite side of the printed circuit board from the key that its light illuminates the key through the bore. In this way, the light source is protected against damage by the thrust pad when the key is actuated, and the delivery of the light from the light source to the key through the bore is ensured.
A further advantage is that the illumination of the key is extinguished when contact is established by actuating the key and if another operating state of the telecommunications terminal is initiated thereby. In this way, the user has a visual means of checking the successful actuation of the key.
A further advantage is that the illumination of the key is extinguished when an incoming call is answered by actuation of the key. In this way, the user has a visual means of checking for successful answering of the incoming call by actuating the key.
Another advantage is that the light source illuminates the key in a blinking manner. In this way, more effective visual signaling is possible, since the user""s attention is drawn more closely to the prevailing operating state of the telecommunications terminal, for example, to the receipt of a call. This is especially important when there is no additional acoustical signaling. The prevailing operating state of the telecommunications terminal is still brought to the user""s attention especially quickly by the blinking light.